Heat oil in a Dutch oven over medium heat; add onion and garlic and sauté until onion is translucent. Add celery and carrot; cook 5 more minutes. Add remaining ingredients and bring to a boil. Reduce heat; cover and simmer 1 1/2 hours or until thickened. Ladle soup into 4 bowls; top each serving evenly with Italian Croutons.
Cube bread and place in a large plastic zipping bag; set aside. Combine butter and seasoning; pour over bread. Mix well; arrange bread cubes on an ungreased baking sheet. Bake at 425° for 10 minutes; turn bread cubes and bake 5 more minutes.